In the petroleum industry, a pig refers to a device inserted into a pipeline to perform a task. Pigs are used to perform various actions upon a pipeline such as clean a pipeline, diagnose problems with the pipeline, or separate various fluids or substances in the pipeline. Frequent pigging cleans the line to allow a higher product flow rate. Pigging can be used when changing from one fluid in the pipeline to another. Using a pig for diagnostic purposes allows for detection of a problem before it is critical. Pigs may be made of various materials.
Typically, pigs are inserted into a pipeline and travel through the pipeline by fluid pressure to another location where the pig may be removed. In some circumstances, pigs are captive and are not removed from the pipeline. Pigs may or may not interrupt the flow of the fluid through the pipeline.
Pigs are typically inserted into the pipeline via a pig launcher. In one type of pig launcher, a pipe of larger diameter than the pipeline to be pigged is used and the launching pipe gradually decreases in diameter to that of the pipeline to be pigged. The pig is placed in the larger diameter pipe. A similar configuration of equipment may be used for pig receiving.
Automated pig launchers are used to provide a number of pigs to be launched separately at a later time. Automated pig launching has the advantage that it is not necessary for an operator to be present. In some automated pig launchers, multiple pigs may be present so that an operator does not need to be present to insert a new pig each time. The pigs may be stacked vertically or horizontally.
A pig launcher may utilize a ball valve. Ball valves are known in the art, and have traditionally been used as an effective mechanism for regulating fluid flow in various conduits. Typically, ball valves are employed to open or close to enable or block a flow of fluid in a variety of applications. Various structural arrangements have been achieved for interrupting fluid flow by twisting a handle of a ball valve, and resuming fluid flow by twisting the handle back again. Ball valves commonly include a body, an adapter, a rotatable ball disposed within the body and adapter, and a stem coupled to the ball. Typically, ball valves include a housing having an inlet port and an outlet port. A throughbore internally connects the inlet port to the outlet port. An inlet conduit and an outlet conduit may be connected to the inlet port and the outlet port respectively. A central chamber is positioned in the path of the throughbore. A ball with a throughbore is positioned within the central chamber. A ball valve is a quarter turn valve. The ball may be rotated by an external handle. When the handle is twisted to align the throughbore of the ball with the path of the throughbore connecting the inlet port and outlet port, the throughbore connecting the ports is uninterrupted and fluid may flow between the inlet and outlet ports. When the handle is twisted so that the throughbore of the ball lies perpendicular to the throughbore connecting the ports, fluid flow is interrupted.
A particular type of ball valve that may be used in certain higher pressure applications incorporates a trunnion ball which has additional mechanical anchoring of the ball at the top and bottom. One particular advantage of a ball valve incorporating a ball and trunnion mechanism is that when spaced in the same longitudinal axis, the trunnions can act to prevent drift upwards or downwards within the ball valve casing by providing a balancing mechanism.
In oil and gas development or operations, time is money. The longer it takes to perform a task the more money that is being spent. The art field is in need of an automatic pig launcher that provides efficiency, cost savings, and safety by not requiring an operator to be present to launch each pig and is easy to access.
An automatic pig launcher that is more ergonomic and requires less equipment to access the magazine will be beneficial. Not having to insert a new pig each time provides efficiency by not requiring operator time, especially when the pig launcher is present a long distance away or in a harsh environment; is safer for the operator as pressure can build up and/or the material in the pipeline may be hazardous; it is better for the environment because there is less release of material in the pipeline into the environment; and it is better for the pipeline as there is less chance for contamination of the line with outside substances.